#include <iostream>
#include <vector>
#include <algorithm>
#include <cmath>
#include <ctime>

const long Size1 = 39L;
const long Size2 = 100 * Size1;
const long Size3 = 100 * Size2;

bool f3(int x)
{
    return x % 3 == 0;
}
bool f13(int x)
{
    return x % 13 == 0;
}

int main()
{
    using std::cout;
    std::vector<int> numbers(Size1);
    std::srand(std::time(nullptr));
    std::generate(numbers.begin(), numbers.end(), std::rand);
    cout << "Sample size = " << Size1 << '\n';
    int count3 = std::count_if(numbers.begin(), numbers.end(), f3);
    cout << "Count of numbers divisible by 3: " << count3 << '\n';
    int count13 = std::count_if(numbers.begin(), numbers.end(), f13);
    cout << "Count of numbers divisible by 13: " << count13 << "\n\n";

    numbers.resize(Size2);
    std::generate(numbers.begin(), numbers.end(), std::rand);
    cout << "Sample size = " << Size2 << '\n';

    class f_mod
    {
    private:
        int dv;
    public:
        f_mod(int d = 1) : dv(d) {}
        bool operator () (int x)
        {
            return x % dv == 0;
        }
    };

    count3 = std::count_if(numbers.begin(), numbers.end(), f_mod(3));
    cout << "Count of numbers divisible by 3 : " << count3 << '\n';
    count13 = std::count_if(numbers.begin(), numbers.end(), f_mod(13));
    cout << "Count of numbers divisible by 13: " << count13 << "\n\n";

    numbers.resize(Size3);
    std::generate(numbers.begin(), numbers.end(), std::rand);
    cout << "Sample size = " << Size3 << '\n';

    count3 = std::count_if(numbers.begin(), numbers.end(),
                           [] (int x) -> bool
    {
        return x % 3 == 0;
    });
    cout << "Count of numbers divisible by 3: " << count3 << '\n';
    count13 = std::count_if(numbers.begin(), numbers.end(),
                            [] (int x) -> bool
    {
        return x % 13 == 0;
    });
    cout << "Count of numbers divisible by 13: " << count13 << '\n';

    return 0;
}
